Batches and maturity dates hang off the product. Which vat, which date, which use-by: it's on the label, and it's the basis of traceability on the day somebody asks for it.
The dispatch day is a hard rule rather than a suggestion. If parcels only leave Monday to Wednesday, the system has to schedule around that — otherwise a box spends the weekend in a depot and arrives as a complaint.
Selling by weight is the norm here and the classic place a system falls over. A piece of about three hundred grams is never exactly three hundred, and the price, the label and the invoice all still have to agree.